Abstract: Disclosed herein is a shift mechanism in a manual transmission having a detent mechanism which comprises a cylindrical holder provided with an opening at its one end, a detent ball accommodated in the holder at the opening and adapted to contact with one of detent grooves, and a compression spring accommodated in the holder and adapted to bias the detent ball against one of the detent grooves. The opening of the holder is inwardly bent at its circumferential edge to form a ball retaining portion for projecting a part of the detent ball therefrom and retaining the detent ball so as not to come out from the opening.

Abstract: A gear-shift mechanism for a transmission unit which includes a fork shaft slidably supported in a housing assembly which is selectively shifted from its neutral position to forward and reverse positions, a detent mechanism for selectively retaining the fork shaft in its neutral and shifted positions, a shift head member slidable on the fork shaft, a one-way engagement mechanism for effecting the engagement between the shift head member and the fork shaft during axial displacement of the fork shaft toward and away from its reverse position, and a shift arm member pivotably mounted to the inner wall structure of the housing assembly and linked with the shift head member to retain an idler gear in its neutral position and engage the same with driving and driven gears. The detent mechanism includes a holder member having a slot in its upper portion and a shaft fixed to the upper side portion of the holder member.

Abstract: Disclosed herein is a shift fork in a transmission for an automobile having a fork body made of steel plate and a pawl member made of resin fixed to the free ends of the fork body and adapted to engage an annular groove defined on the outer circumference of a hub sleeve included in a clutch mechanism for the transmission.The pawl member has a stepped portion formed at the opposed portion to the outer peripheral edge of the annular groove so as not to abut against the outer peripheral edge during a shift operation.

Abstract: A rotary shaft having a bearing surface and an oil seal surface formed close to each other at a portion of a shaft body rotatably mounted in a case of a transmission, wherein a groove is circumferentially formed on the periphery of the shaft body between the bearing surface and the oil seal surface before each of the surfaces is finished, so that the bearing surface and the oil seal surface can be finished so as to be suitable for their respective functions.

Abstract: A gear-shift mechanism for a power transmission unit includes a fork shaft slidably supported from a housing assembly to be selectively shifted from its neutral position to forward and reverse positions, a detent mechanism for selectively retaining the fork shaft in its neutral and shifted positions, a shift head member slidable on the fork shaft, a one-way engagement mechanism for effecting engagement of the shift head member with the fork shaft in axial movement of the fork shaft to and away from its reverse position, and a shift arm member pivoted to the inner wall structure of the housing assembly and linked with the shift head member to retain an idler gear in its neutral position and to engage the same with driving and driven gears.

Abstract: A gear-shift mechanism for a power transmission unit includes a fork shaft slidably supported from a housing assembly to be selectively shifted from its neutral position to forward and reverse positions, a detent mechanism for selectively retaining the fork shaft in its neutral and shifted positions, a shift head member slidable on the fork shaft, a one-way engagement mechanism for effecting engagement of the shift head member with the fork shaft in axial movement of the fork shaft to and away from its reverse position, and a shift arm member pivoted to the inner wall structure of the housing assembly and linked with the shift head member to retain an idler gear in its neutral position and to engage the same with driving and driven gears. The shift arm member is formed with a cam face, and a spring loaded cam follower is assembled within the inner wall structure to be in engagement with the cam face of the shift arm member to effect disengagement of the idler gear from the driving and driven gears.

Abstract: In an hydraulic release mechanism for a vehicle clutch, a seal member is adapted to a transmission housing assembly to surround an extended portion of a push-rod in a fluid tight manner, and an hydraulic cylinder includes a cylinder housing provided at its closed end with a port for connection to a source of hydraulic pressure and being detachably secured to the housing assembly at its open end to contain one end of the push-rod therein, and a piston axially slidable within the cylinder housing through an annular seal member to subdivide the interior of the cylinder housing into a pneumatic chamber in open communication with the atmospheric air and an hydraulic chamber in open communication with the port, the piston being engaged with the one end of push-rod to urge the push-rod toward a release member of the vehicle clutch.

Abstract: A shift fork support structure in a manual transmission of such a type that a shift fork is axially slidable on a fork shaft comprising a bushing press-fitted into apertures formed on the shift fork and engaging the fork shaft. The inner peripheral surface of the bushing is coated by Teflon layer. With this structure, the frictional resistance between the shift fork and the fork shaft may be reduced, thus permitting the shift fork to be smoothly operated.